Writing instrument



FIG. 1 is a side view of the writing instrument with its cover;

FIG. 2 is a perspective view of the writing instrument without its cover; and,

FIG. 3 is a perspective view of the cover of the writing instrument. The articles in FIGS. 2 and 3 have been shown separately for ease of illustration. 

The ornamental design for writing instrument, as shown and described. 